You may have followed home brewing instructions to the ‘T’ from the very beginning but it helps to know why you are doing things when brewing beer… knowing why oxygen is wanted in your wort is one of those things that can help you solve a lot of your brewing problems…

… but before we get to far into this topic, let’s get one thing clear… Oxygen is ONLY wanted in beer at one single point in the brewing process… and that is right before you pitch your yeast and after you have cooled your wort after the boil…

The thing is that oxygen dissolves into wort much better when it’s cold. In fact, when you boil your wort you drive off most of the oxygen which is the reason why we need to aerate our wort and inject oxygen back into it.

But what does oxygen do for us anyway?

Well to answer that, here are the top 3 reasons to aerate your wort…

Shorter Lag Times
Yeast need oxygen to grow and reproduce… and they must grow and reproduce before they can begin to ferment your beer.

By providing oxygen to your wort you are essentially helping your yeast grow and reproduce which will shorten the lag time between the time you pitch your yeast and the time you begin to see fermentation happening.

Often times you’ll hear new brewers say that they see no airlock activity 36 hours after pitching yeast and it usually has to do with poor aeration of the wort. In summary, lack of oxygen of the wort can lead to long lag times.

Full or Complete Fermentation
Pitching the right amount of yeast into your wort is a MUST if you want to fully ferment your beer. This is one of the most important aspects you look for in brewing software or calculators, but there is a catch…

Yeast pitching equations, calculators and brewing software assumes that you fully aerate your wort so that the yeast grow and reproduce to the right amount of cells so they can fully attenuate your beer. If you don’t aerate your wort and your yeast don’t reproduce to the right amount of yeast cells then you may end up with a stuck or incomplete fermentation…

… that’s not a good thing…

Good Ester Production
Virtually all yeast produce esters during fermentation, including ‘clean’ yeast strains. One thing that can affect ester production is the amount of yeast cells in the wort fermenting the beer. See even if you dodge the lag times and stuck fermentations from a poorly aerated wort, your beer may still be subject to excessive ester production.

The less amount of yeast cells you have fermenting your beer the more esters it will produce. This is the fruit flavor, which although may be desired in some styles of beer it should never be excessive.

Aerating your wort doesn’t require you spending hundreds of dollars on pure oxygen systems, pumps and what not. I wrote a blog post on how to aerate your wort, and I cover the 3 best ways to get oxygen into your beer to ensure a good fermentation.

… and remember that you only want oxygen right before you pitch your yeast and after you’ve cooled your wort… any other time you’ll be increasing your chances of oxidating your beer and getting off-flavors… cheers!


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